Yea I give up on it. After a looong phone conversation were i was transferred 4 times and finally hung up on. They couldnt even give me the specks on the springs but, ohwell i didnt pay for the pump anyhow and I know what brand not to buy in the futur.
Also, the last time I looked on ebay there were tons of broken Robinair pumps for parts. You might try that and keep checking if nothing is there now. Most of those pumps have bad vanes so chances are good they have the spring you need.